Green roofs are being studied as a means to increase vegetation and preserve aesthetics in old Mediterranean cities. In order to preserve ancient cities' local character and biodiversity, researchers are looking to native plant species that can withstand the low water environments that are necessary in lightweight green roof design.
Xerophytes--species of plants that have adapted to survive in environments with little water--fit well in green roof construction plans, creating lightweight roofs that don't compromise ancient buildings' structural concerns.
A research team in Athens explored the use of three Mediterranean aromatic xerophytes, Artemisia absinthium, Helichrysumitalicum, and H. orientale, for use in an extensive green roof design. The study, published in HortScience, also investigated the practice of using of locally produced grape marc compost to promote drought resistance, and looked at the effects of different planting depths and irrigation frequencies on the three aromatics.
According to the Maria Papafotiou from the Department of Crop Science at the Agricultural University of Athens, most Mediterranean cities are centered around their old nucleus, which in many cases is characterized as a historical heritage. "These cities lack areas that could be converted into conventional green spaces, and thus there is an increasing interest in green roof systems. Green roofs are still relatively uncommon in Mediterranean countries, although these areas would significantly benefit from the ecological and technical functions of this technology," Papafotiou explained.
The scientists planted rooted cuttings of the three aromatics in a green roof infrastructure they then placed on a fully exposed flat roof in Athens. Two types of substrates were used (grape marc compost:soil:perlite and peat:soil:perlite ) at two substrate depths, 7.5 cm (shallow) and 15 cm (deep). The team applied two irrigation frequencies throughout the study: sparse (5 or 7 days in shallow and deep substrate, respectively) and normal (3 or 5 days in shallow and deep substrate, respectively), and recorded plant growth from May to October.
Results showed that all three of the plant species were established successfully on the green roof under all experimental treatments, although Artemisia absinthium generally showed the greatest growth as indicated by the final diameter and height of the plants. "With A. absinthium, grape marc compost-amended substrate produced taller plants and larger plant diameter compared with peat-amended substrate, deep substrate produced larger plant diameter compared with shallow substrate, and normal irrigation produced taller plants compared with sparse irrigation," the researchers said. "In both Helichrysum species, we found there were interactions of the main factors in almost all growth parameters; therefore, the only conclusion we drew concerning factor effects was that irrigation frequency did not affect the diameter and the dry weight of H. italicum plants."
The researchers noted that a "remarkable result" was that shallow compost-amended substrate with sparse irrigation resulted in similar or even bigger plant growth of all plant species compared with deep peat-amended substrate with normal irrigation.
"We determined that all three aromatic species were suitable for use in Mediterranean extensive or semi-intensive green roofs, and additionally found that the use of grape marc compost in the substrate allowed for less water consumption and the reduction of substrate depth without restriction of plant growth at the establishment phase and the first period of drought," Papafotiou said.
The complete study and abstract are available on the ASHS HortScience electronic journal web site: http://hortsci.ashspublications.org/content/48/10/1327.abstract
Founded in 1903, the American Society for Horticultural Science (ASHS) is the largest organization dedicated to advancing all facets of horticultural research, education, and application.
Mike W. Neff | EurekAlert!
Sequencing of barley genome achieves new milestone
26.08.2015 | University of California - Riverside
Entomologists sniff out new stink bug to help soybean farmers control damage
25.08.2015 | Texas A&M AgriLife Communications
A University of Oklahoma astrophysicist and his Chinese collaborator have found two supermassive black holes in Markarian 231, the nearest quasar to Earth, using observations from NASA's Hubble Space Telescope.
The discovery of two supermassive black holes--one larger one and a second, smaller one--are evidence of a binary black hole and suggests that supermassive...
A team of European researchers have developed a model to simulate the impact of tsunamis generated by earthquakes and applied it to the Eastern Mediterranean. The results show how tsunami waves could hit and inundate coastal areas in southern Italy and Greece. The study is published today (27 August) in Ocean Science, an open access journal of the European Geosciences Union (EGU).
Though not as frequent as in the Pacific and Indian oceans, tsunamis also occur in the Mediterranean, mainly due to earthquakes generated when the African...
In mountainous regions earthquakes often cause strong landslides, which can be exacerbated by heavy rain. However, after an initial increase, the frequency of these mass wasting events, often enormous and dangerous, declines, in fact independently of meteorological events and aftershocks.
These new findings are presented by a German-Franco-Japanese team of geoscientists in the current issue of the journal Geology, under the lead of the GFZ...
Bacteria do not cease to amaze us with their survival strategies. A research team from the University of Basel's Biozentrum has now discovered how bacteria enter a sleep mode using a so-called FIC toxin. In the current issue of “Cell Reports”, the scientists describe the mechanism of action and also explain why their discovery provides new insights into the evolution of pathogens.
For many poisons there are antidotes which neutralize their toxic effect. Toxin-antitoxin systems in bacteria work in a similar manner: As long as a cell...
It comes when called, bringing care utensils with it and recording how they are used: Fraunhofer IPA is developing an intelligent care cart that provides care staff with physical and informational support in their day-to-day work. The scientists at Fraunhofer IPA have now completed a first prototype. In doing so, they are continuing in their efforts to improve working conditions in the care sector and are developing solutions designed to address the challenges of demographic change.
Technical assistance systems can improve the difficult working conditions in residential nursing homes and hospitals by helping the staff in their work and...
20.08.2015 | Event News
20.08.2015 | Event News
19.08.2015 | Event News
28.08.2015 | Physics and Astronomy
28.08.2015 | Health and Medicine
28.08.2015 | Life Sciences